There are two basic methods of cork pad installation; floatng them in, or sanding them in.  To float in a pad requires a slightly thinner pad, so that there is room in the key cup for a layer of shellac or firm hot glue.  Most factories use this method, which is faster (Lorée and Covey are some of the few who use the sanding method).  Floating requires the cork pad to be sanded flat first, and then adjusted to the tone hole by shifting it around on the warm glue.  The main advantage to floating is ease of installation, and speed.   The main disadvantage is that the pads can shift slightly out of position if someone carelessly leaves the instrument in a hot car. 

Sanding in a pad requires a somewhat thicker pad.  It is installed with a snug fit, and pressed to the bottom of the key cup with just a small amount of glue, usually shellac.  The key is then placed on the instrument, and the pad lightly pressed against the tone hole.  The key is then removed so that the pad can be sanded where it hits first, as evidenced by the dent made by the tone hole, or by the usual cigarette paper check.  The sanding is done with fine sandpaper glued to one end of a flat strip of metal, the other end held as a handle.   

The main advantage to the sanding in method, is that the pad is not likely to shift in a hot car situation.  It is the more solid installation.  The main disadvantage is that it is extremely time consuming, usually requiring each new pad to by tried on the instrument, and sanded, multiple times.  Other problems are “dig ins” with the sandpaper, and rounding over the pad, rather than keeping it flat.  Also, the cork can swell, shrink, and warp with the climate.  So can the grenadilla tone hole, negating all the advantage to the sanding in method.

Personally, I don’t have the time, nor wealthy enough patrons to sand in pads very often.  I use the floating method to install my pads.  I have done an experiment with various glues left in a hot car, and have found a firm hot glue to hold it’s shape better than shellac.  Also, the hot glue is more easily cleaned up if it gets on the sides of the pad.  You may be interested to know that shellac is the secretions of the lac beetle.  Yummy.

So, here are the steps to installing a pad by the floating method:

1.  Choose a pad as evenly textured as possible.  Squeeze the pad between your thumb and index finger.    A firmer pad will be denser, and probably more airtight, than a soft pad.  Discard the softest pads. 

2.  Sand the pad to create a flat even seat.  I hot glue the pad to a brass rod, which I put into a dremel tool.  Then I hold a brass stick covered with smooth sandpaper to the revolving pad.  The diameter of the pad can also be modified while revolving.  Make sure the best side of the cork is used for the tone hole seat. 

3.  Apply enough hot glue or shellac to the pad to float it in.  Too little, and it won’t shift enough.  Too much, and it oozes out, making a mess.  A little experience will tell.  I use an acetylene torch, but any heat source should work.

4.  Install the pad in the key, and heat the key with the flame tangiential to the wood, so as not to burn the grenadilla.  Move the pad around with a pad slick (thin piece of steel) or a reed plaque for smaller pads, until the pad is level with the tone hole.  Use a thin strip of  cigarette paper to check that the pad will lightly touch the tone hole all around.